This invention relates to a lightweight unitary metal building truss.
Metal trusses for buildings have been in use but structurally they have been relatively heavy due to either the gauge of steel used and/or the number of fasteners needed to fasten the chords and diagonals. Further, the width of the steel studs used are on the magnitude of 3.625 inches with the bottom chord of the truss of a 4 inch width.
In addition the prior art includes wooden trusses which are of course even heavier than the prior art metal trusses.
As an illustration of the weight factors a 20 foot truss span which has a standard 4:12 pitch has a weight of approximately 115 lbs. The "4:12 pitch" refers to a standard in the industry that the truss rises 4 feet for every 12 feet of horizontal length of the truss to the center point. A 20 foot truss fabricated from metal with the same pitch posseses a weight of approximately 60 lbs. In addition the metal used has been that of 18 gauge steel. As used herein "18 gauge" means the thickness of the steel which is approximately 1.52 mm or 0.0478 inches. The steel referred to herein is hot dipped galvanized strip steel.
Other illustrations of approximate weight are as follows:
______________________________________ 28' Truss Span 32' Truss Span ______________________________________ Prior Art Metal 82 lbs. 97 lbs. Wood 210 lbs. 240 lbs. ______________________________________